NLTK before 3.10.3 SSRF Protection Bypass via Proxy
NLTK before 3.10.3 contains a server-side request forgery vulnerability in nltk.pathsec.urlopen (and callers nltk.data.load, nltk.downloader.Downloader.index/download) when an HTTP proxy is configured. pathsec.urlopen validates the requested hostname locally, but proxy-handler inheritance disables the safe HTTP/HTTPS handlers so the actual fetch is performed by the proxy against a destination that is never re-validated. An attacker can supply a validated public URL that the proxy forwards to an internal loopback-only service, allowing disclosure of internal HTTP resources, loading of forged downloader indexes, and installation of attacker-chosen package content.
CVE-2026-78682
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-78682
nltk
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"vendor": "nltk",
"product": "nltk",
"versions": [
{
"status": "affected",
"version": "0",
"lessThan": "3.10.3",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "3.10.3",
"versionType": "semver"
}
],
"packageURL": "pkg:pypi/nltk",
"defaultStatus": "unaffected"
}
]- Related CVEs
- CVE-2026-78682
Source reference:
/cveMetadata/cveId
Publisher severity
high
Source reference: /containers/cna/metrics
- Event
- #12891 · Revision 1
- Added to Heist Feed
- Publisher date